Plastic fastener with slider and bag body with plastic fastener

ABSTRACT

The present invention relates to a plastic zipper equipped with a slider, and a bag body equipped with the above plastic zipper, and the object of the invention is to provide a plastic zipper equipped with a slider which zipper is required to have a strong opening force despite its miniaturization. The object is achieved in a hermetically sealing plastic zipper equipped with a slider (S) for opening and closing the zipper, comprising a pair of male hook and female hook (F 1 - 1 , F 1 - 2 , M 1 - 1 , M 1 - 2 ), by installing flanges on the opening portion sides for each of the male and female hooks, connecting the respective ends of the flanges, and pressing a wedged opening plate into the inside of a closed plastic cylinder which is constituted of the flange portions connected respective ends thereof and extended to the zipper in an engaged state so that the zipper is firstly opened and after the zipper is opened, the top portion of the flanges in a connected state is disconnected.  
     The above plastic zipper equipped with the slider has an extremely high opening strength despite its miniaturization and thereby is capable of easily open a zipper in which hooks or opening end edges are bonded with easily peelable plastic layers for the purpose of preventing unjust unsealing and which has a strong opening strength.

TECHNICAL FIELD

[0001] The present invention relates to a plastic zipper equipped with aslider which zipper is employed as packaging materials for foods,pharmaceuticals, electronic part items and the like, and which iscapable of keeping hermetical sealability even after repeated openingand closing operations, and which enables easy opening and resealing. Italso pertains to a bag body equipped with the above-mentioned plasticzipper.

BACKGROUND ART

[0002] There are widely employed, as packaging materials for a varietyof articles in the fields of foods, pharmaceuticals, electronic partitems and the like, bag bodies each equipped on the opening portion witha plastic zipper composed of a pair of male and female hooks on asurface of a plastic film. In particular, there are widely employedplastic zippers each equipped with a slider which is used for openingand closing the zippers because of easiness in opening and closingoperations.

[0003] This slider is composed of an outside guide and an inside guide.The slider which is usually employed is of such a structure that theinside guide is inserted between the male and the female hooks andcauses the male/female hooks to disengage, while the outside guidecauses the male/female hooks to engage {refer to Japanese PatentApplication Laid-Open No. 214920/1996 (Heisei 8)}.

[0004] Since in the slider of the conventional structure, the insideguide is inserted between the hooks of a zipper, even if the zipper iscompletely bound tight, the content in a bag leaks through a gap betweenthe hooks and the inside guide which is inserted between the hooks.Hence, the above-mentioned zipper is unusable for applications requiringhermetical sealing except for applications only not requiring hermeticalsealing such as general cargoes.

[0005] On the other hand, there is proposed a zipper having such astructure that hermetical sealing can be maintained in a state of a bagbeing closed with a slider by the use of a specially shaped plasticzipper and a slider adapted thereto (for instance, U.S. Pat. Nos.5,067,208 and 5,664,299).

[0006] In the plastic zippers as disclosed therein, hermeticalsealability is maintained by taking advantage of the elasticity of theplastic material which constitutes the zipper for the purpose offacilitating the disengagement even with a weak force, and thereforewhen the elasticity thereof varies with a variation in temperature orthe like, there is caused a fear of incapability of maintaining thehermetical sealability after opening and closing operations, whereby theamount of leakage is increased. Such being the case, the above-proposedzippers are unusable for packaging such content as liquid and the likein which occurrence of leakage is forbidden.

[0007] The present inventor previously proposed a hermetically sealableplastic zipper characterized by forming male hooks and female hooks ofthe zipper on the surface of a plastic, forming a continuous tighteningwall parallel to the male hooks on the inside thereof, and furtherforming a continuous pressing rib parallel to the female hooks on theinside thereof, so that the zipper is imparted with excellent propertiesin persistent hermetical-sealability and also impact resistance by thetight contact between the continuous tightening wall and the continuouspressing rib as well as self-tightening effect thereof (Japanese PatentRegistration No. 2,938,784). The hermetically sealable plastic zipper isexcellent in hermetical sealability and impact resistance and almostfree from performance variation due to temperature variation, andaccordingly is well suited for packaging liquid and the like.

[0008] In addition, the present inventor previously proposed a slidershown in Japanese Patent Application Laid-Open No. 130594/2001 (Heisei13)} which was adapted to the aforesaid hermetically sealable plasticzipper and which does not impair the hermetical sealability thereof, anda plastic zipper equipped with the above-mentioned slider. Theconstitution thereof is such that as illustrated on FIG. 10, protrusionsG2-1, G2-2 each serving as a guide for the slider are installed on theopening portion side flange portion (extension portion) of opening sidehook so that the protrusions are parallel to the slider, and also aninside guide S-1 is installed on the plate portion C of the slider S sothat the inside guide is positioned between the protrusions and thehooks on the side of the opening portion of the zipper, so as to enablethe hermetically sealable plastic zipper to be opened and closed bysliding the slider S as illustrated on FIG. 12 and FIG. 13.

[0009] However, the plastic zipper equipped with said slider and a bagbody equipped with said zipper suffer from the disadvantage in thatunjust unsealing is unpreventable, since the plastic zipper in a closedstate can readily be opened by pulling the aforesaid protrusions G2-1,G2-2 with the slider S from the outside of the zipper.

[0010] The aforesaid slider of such constitution that enables unjustunsealing even after being closed involves a fear of causingcontamination with foreign matters or abnormal quality due to unjustunsealing. Thus in order to eliminate the disadvantage, the presentinventor previously proposed a plastic zipper which was equipped with aslider and which was capable of performing completely sealed packagingwith a zipper alone and of detecting that unsealing had been made afterthe sealed packaging, and a bag body equipped with the zipper {refer toJapanese Patent Application Laid-Open No. 345057/2000 (Heisei 12)}.

[0011] As exemplified on FIG. 14 through 17, the plastic zipper which isequipped with a slider and a means for detecting unjust unsealing and abag body equipped with the zipper each comprise a pair of male hook andfemale hook formed on a plastic surface, have a continuous tighteningwall 1-2 and a continuous pressing rib 1-4 that are parallel to the malehooks 1-1 on the inside thereof, and are equipped with a means forbonding the surfaces of the continuous tightening wall 1-2 and thecontinuous pressing rib 1-4 with easily peelable plastic layers A-1, B-1in a state of the zipper being engaged and a means for bonding theprotrusions G2-1, G2-2 each serving as a guide for the slider that areformed parallel to a pair of male and female hooks 5-1, 5-2 on theplastic surfaces with easily peelable plastic layers A-8, B-8 in a stateof the zipper being engaged.

[0012] The above-mentioned means are capable of easily opening andclosing the zipper by means of the slider as disclosed in the aforesaidJapanese Patent Application Laid-Open No. 130594/2001 after the easilypeelable plastic layers are peeled off. However, in order to steadilycarrying out the peeling of the easily peelable plastic layers with theaforesaid slider, the opening force of the slider needs to be greatlyincreased by reason of unstable peeling force of the easily peelableplastic layers. Hence, the protrusions serving as a guide for the sliderand the inside guide for the slider must be large-sized, thus bringingup the problem in that said slider is unusable for a small bag.

[0013] Japanese Patent Registration No. 3,026,839 describes a method foropening and closing the zipper fitted with a rib on the end portion of aflange attached to the opening side of the zipper by the use of a sliderhaving a vertical lower side wall portion and a member in inverse Ushape. The method, although being easy to obtain the opening force, isrequired to enlarge the member in inverse U shape inside the slider,when applied to the hermetically sealable zipper which is disclosed inthe aforesaid Japanese Patent Registration No. 2,938,784 relating to theproposal of the present inventor and which is excellent in hermeticalsealability and the like. Consequently the method is unapplicable to asmall bag.

[0014] The present inventor proposed a plastic zipper equipped with aslider and imparted with a means for preventing unjust unsealing,characterized in that the plastic zipper which is equipped with a sliderand a pair of male and female hooks for sealing formed on plasticsurfaces is fitted with a pair of male and female hooks for guiding theslider parallel to the hooks for sealing on the opening side, and theinside guide for the slider is positioned between the hooks for sealingand the hooks for guiding the slider {Japanese Patent ApplicationLaid-Open No. 375501/2000 (Heisei 12)}.

[0015] The constitution of the aforesaid plastic zipper is such that thehooks for guiding the slider is firstly opened, and the hooks forsealing are opened by catching the inside guide for the slider on thehooks for guiding the slider thus opened. It is possible tosimultaneously use these inventions, that is, to install a pair of maleand female hooks for guiding the slider parallel to the hooks forsealing on the opening side of the plastic zipper in which the surfacesof the above-mentioned continuous tightening wall and continuouspressing rib are bonded with easily peelable plastic layers.Nevertheless, as is the case with the slider mentioned before, theslider just mentioned involves the problem of being unapplicable to asmall bag. Under such circumstances, the development of a plastic zipperequipped with a slider capable of markedly increasing an opening forcein spite of its being miniaturized has eagerly been desired.

DISCLOSURE OF THE INVENTION

[0016] As a result of intensive research and investigation, the presentinventor have developed a plastic zipper equipped with a slider capableof markedly increasing an opening force in spite of its beingminiaturized and a bag body equipped with said zipper, in order to applya plastic zipper equipped with a slider to a small bag without impairingthe characteristics of the zipper even if the zipper has an extremelyhigh opening strength as is the case with a hermetically sealable zipperin which the above-mentioned continuous tightening wall and continuouspressing rib are bonded with easily peelable plastic layers.

[0017] The means for solving the subject are summarized as follows.

[0018] 1. In a hermetically sealing plastic zipper equipped with aslider whereby the zipper is opened and closed, comprising a pair ofmale hook and female hook formed on plastic films, installing flanges onthe opening portion sides for each of the male hook and female hookthereof, connecting the respective ends of the flanges, and pressing awedged opening plate into the inside of a closed plastic cylinder whichis constituted of the flange portions connected respective ends thereofand extended to the hermetically sealing plastic zipper in an engagedstate so that the hermetically sealing zipper is firstly opened andafter the hermetically sealing zipper is opened, the top portion of theflanges in a connected state is disconnected.

[0019] 2. In the hermetically sealing plastic zipper equipped with aslider as set forth in the item 1, maintaining the hermeticalsealability of the zipper by not allowing to form a closed plasticcylinder which is constituted of the flange portions connected to thehermetically sealing plastic zipper in an engaged state at the point oftime and position where the opening end of the slider reaches theclosing end of the hermetically sealing zipper by the sliding operationof the slider.

[0020] 3. In the hermetically sealing plastic zipper equipped with aslider as set forth in the item 2, making a slit at a portion of theflanges corresponding to the opening plate at the closing end positionof the hermetically sealing zipper so as not to allow the closed plasticcylinder to be formed.

[0021] 4. In the hermetically sealing plastic zipper equipped with aslider as set forth in the item 1, installing a second zipper or a ribat the end portions of each of the flanges at the opening portion sideof the male hook and female hook for the hermetically sealing zipper inan engaged state in order to connect said end portions.

[0022] 5. In the hermetically sealing plastic zipper equipped with aslider as set forth in the item 4, maintaining connected state of theend portions of each of the flanges at the opening portion side of themale hook and female hook for the hermetically sealing zipper in anengaged state by installing a connecting groove parallel to thehermetically sealing zipper above the opening plate for the slider,placing a second zipper or a rib in the connecting groove, andinstalling a cover on the opening portion of the connecting groove.

[0023] 6. In the hermetically sealing plastic zipper equipped with aslider as set forth in the item 4, maintaining the hermeticalsealability of the zipper by not allowing to form a closed plasticcylinder which is constituted of the flange portions connected to thehermetically sealing plastic zipper in an engaged state at the point oftime and position where the opening end of the slider reaches theclosing end of the hermetically sealing zipper by the sliding operationof the slider.

[0024] 7. In the hermetically sealing plastic zipper equipped with aslider as set forth in the item 5, crushing to flatness or cutting offthe portion of the second zipper or the rib corresponding to the openingplate at the closing end position of the zipper so as not to allow theclosed plastic cylinder to be formed.

[0025] 8. Installing the hermetically sealing plastic zipper equippedwith the slider as set forth in the item 1 on an opening portion of abag body.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a schematic perspective view showing a partially cutawaybag body equipped with a plastic zipper fitted with a slider;

[0027]FIG. 2 is a cross sectional view taken along line A-A′ of FIG. 1;

[0028]FIG. 3 is a cross sectional view taken along line B-B′ of FIG. 1;

[0029]FIG. 4 is a cross sectional view taken along line C-C′ of FIG. 1;

[0030]FIG. 5 is a cross sectional view which corresponds to FIG. 3 andin which a rib of a different shape is installed in place of a secondzipper;

[0031]FIG. 6 is a fragmentary sectional view of FIG. 5;

[0032]FIG. 7-1, 7-2 are each a cross sectional view for the purpose ofexplaining the dimensional relationship of each of portions;

[0033]FIG. 8 is a cross sectional view showing a configuration for thepurpose of not allowing a plastic cylinder to be formed at a closing endposition of a hermetically sealing plastic zipper;

[0034]FIG. 9 is a cross sectional view showing another configuration forthe purpose of not allowing a plastic cylinder to be formed at a closingend position of a hermetically sealing plastic zipper;

[0035]FIG. 10 through FIG. 13 are each a perspective view showing aplastic zipper fitted with a slider and a slider proposed by the presentinventor and shown in Japanese Patent Application Laid-Open No.130594/2001; and

[0036]FIG. 14 through FIG. 17 are each a perspective view showing aplastic zipper fitted with a slider and a slider which were proposed bythe present inventor and shown in Japanese Patent Application Laid-OpenNo. 345057/2000.

DESCRIPTION OF THE SYMBOLS IN THE DRAWINGS

[0037] F: plastic film

[0038] F1-1, F1-2: female hook for a hermetically sealing plastic zipper

[0039] M1-1, M12: male hook for a hermetically sealing plastic zipper

[0040] F2: female hook for a second zipper

[0041] M2: male hook for a second zipper

[0042] R1: continuous pressing wall

[0043] R2: continuous pressing rib

[0044] S: slider

[0045] S1: opening plate

[0046] S2: cover

[0047] S3: opening stanchion

[0048] S4: connecting groove

[0049] S5: protrusion for preventing falling off

[0050] S6: closing wall for a hermetically sealing plastic zipper

[0051] S7: closing wall for a second zipper

[0052] B: rib

[0053] E1: opening end of a zipper

[0054] E2: closing end of a zipper

THE MOST PREFERRED EMBODIMENT TO CARRY OUT THE INVENTION

[0055] The embodiments of the present invention will be described withreference to FIG. 1 through FIG. 9. FIG. 1 is a schematic perspectiveview showing a partially cutaway bag body equipped with a plastic zipperfitted with a slider. FIG. 2 through FIG. 4 are each a cross sectionalview taken along line A-A′ of a slider opening end in FIG. 1, a crosssectional -view taken along line B-B′ of an opening plate in FIG. 1, anda cross sectional view taken along line C-C′ of the slider closing endin FIG. 1, respectively. FIG. 5 and FIG. 6 are each a cross sectionalview and a fragmentary sectional view, respectively, both correspondingto FIG. 3 and illustrating a rib of a different shape instead of asecond zipper.

[0056] In these figures, F is a plastic film, F2/M2 are each a femalehook in a second zipper and a male hook in the same, respectively. F1-1and F1-2 are each a female hook for a hermetically sealable plasticzipper, M1-1 and M1-2 are each a male hook for the hermetically sealablezipper, respectively, R1 and R2 are each a continuous pressing wall anda continuous pressing rib, respectively, S is a slider, S1 is an openingplate, S2 is a cover, S3 is an opening stanchion, S4 is a connectinggroove, S5 is a protrusion for preventing falling off, S6 is a closingwall for a hermetically sealing plastic zipper, S7 is a closing wall fora second zipper, B is a rib, E1 is an opening end of a zipper and E2 isa closing end of a zipper.

[0057] As illustrated on FIG. 1, a hermetically sealing zipper CH1 isformed on the surface of the plastic film F, which comprises the pairsof male and female hooks F1-1, F1-2, M1-1, 1-2; the continuous pressingwall R1; and the continuous pressing rib R2. In a plastic zipperequipped with a slider, the hermetically sealing zipper is opened andclosed by means of the slider S, a flange (extension portion) FL isinstalled on each opening portion side of male and female hooks for thehermetically sealing zipper CH1, and a second zipper CH2 composed of apair of male and female hooks is installed on each end portion of theflange FL.

[0058] In this case, when the slider S is slid towards the closing endof the zipper E2, the hermetically sealing zipper and the second zipperare closed. Conversely, when the slider S is slid towards the openingend of the zipper E1, both the zippers are opened.

[0059] In the above-mentioned plastic zipper equipped with the slider,when the slider S is slid towards the closing end of the zipper E2, theclosing wall for the hermetically sealing plastic zipper S6 and theclosing wall for a second zipper S7 that are installed on the crosssection C-C′ in FIG. 4 cause the male and female hooks to engage witheach other, so that the hermetically sealing zipper and the secondzipper are closed almost simultaneously.

[0060] Conversely when the slider S is slid towards the opening end ofthe hermetically sealing zipper E1, as illustrated on FIG. 4, the wedgedopening plate S1 illustrated on FIG. 3 is firstly pushed into the insideof a closed plastic cylinder FP which is constituted of the flangeportions that are connected with the hermetically sealing zipper and thesecond zipper each in an engaged state, and thereby the hermeticallysealing zipper is opened. However, the second zipper CH2 still remainsunopened at this step, since it is housed in the connecting groove S4and is pressed by the cover S2.

[0061] The width of the connecting groove S4 used for keeping a closedstate of the hermetically sealing zipper CH1 after its opening is madelarger than the width of the opening stanchion S3 immediately in frontthereof, whereby the function of the groove for opening prevention issubstantially eliminated or the connecting groove itself is removed.Thereafter as illustrated on FIG. 2, the opening stanchion B3 is used toopen the second zipper CH2, whereby the bag equipped with the zipper isopened.

[0062] Although the function was explained with reference to thehermetically sealing zipper CH1 and the second zipper CH2, a rib Billustrated on FIG. 5 or FIG. 6 may be used in place of the secondzipper CH2. The shape of the rib B is not limited to rectangle, but maybe of a different shape such as triangle or semicircle. In addition, thehermetically sealing zipper, which has been exemplified by a specialhermetically sealing zipper as disclosed in Japanese Patent RegistrationNo. 2,938,784, is not limited thereto. Likewise, the second zipper isnot limited to the zipper as exemplified hereinbefore. That is to say,each of the zippers may be of any type. Needless to say, the zipperaccording to the present invention is applicable to a bag body equippedwith a zipper in which the plastic zipper according to the presentinvention is formed in a tape form, and is fusedly bonded into a bagbody at a lower portion of a the zipper.

[0063] When the slider opening end A-A′ reaches the closing end E2 ofthe hermetically sealing zipper in FIG. 1, a portion of the secondzipper or the rib which portion comes in contact with the opening plateis crushed to flatness by means of heat seal or the like oralternatively, the second zipper or rib is cut off at the position ofthe closing end E2, thereby as illustrated on FIG. 8, not allowing toform a closed plastic cylinder which is constituted of the flangeportions connected to the second zipper or the rib and the hermeticallysealing plastic zipper in an engaged state at the closing end positionof the hermetically sealing zipper. Consequently, since the top side ofthe flange is made mobile thereby even if widened by the opening plate,any force of opening the underside of the hermetically sealing plasticzipper is never generated, whereby hermetical sealability thereof can bemaintained.

[0064] In addition to the foregoing, when the slider opening end A-A′reaches the closing end E2 of the hermetically sealing zipper, a slit SLis made in a portion of the flange FL between the second zipper or therib and the hermetically sealing zipper CH1 at the position of theclosing end E2, thereby as illustrated on FIG. 9, not allowing to form aclosed plastic cylinder which is constituted of the flange portionsconnected to the second zipper or the rib and the hermetically sealingzipper in an engaged state at the closing end position of thehermetically sealing zipper. Consequently, since the top side of theflange is made mobile thereby even if widened by the opening plate, anyforce of opening the underside of the hermetically sealing plasticzipper is never generated, whereby hermetical sealability thereof can bemaintained.

[0065] The above-mentioned slit according to the present invention,although seemingly resembles the slit or notch described in JapanesePatent Registration No. 3,026,839, is fundamentally different therefromin terms of its function. Specifically in the method in the JapanesePatent Registration No. 3,026,839, it is a prerequisite to open a rib atthe end of a flange to open a zipper, and the significance of theexistence for the slit or notch is not to allow the rib to open, or todisconnect the zipper therefrom even if the rib is opened.

[0066] In the present invention, as opposed to the foregoing, the rib atthe end of the flange portion is not opened but is consistently closedat the time of opening the zipper or actuating the slit or notch,differently from the method in the Japanese Patent Registration No.3,026,839. Specifically, the slit or notch according to the presentinvention exists not to allow to form a closed plastic cylinder which isconstituted by connecting the flexible flange portions, therebyrendering itself entirely different from that of said Patent in terms ofits function and structure.

[0067] On the other hand, the slit or notch as described in JapanesePatent Application Laid-Open No. 503672/1998 (Heisei 10) is constitutedsuch that a cantilever flange having rigidity and one opening fulcrum isinstalled on the opening side of the zipper, and is made into an inverseT-shaped separate structure so that the function of said separatestructure is invalidated with the the slit or notch by opening the rigidcantilever flange at the time of opening a zipper.

[0068] In the present invention, as opposed to the foregoing, the zipperis opened by pushing the wedged opening plate into the inside of aclosed plastic cylinder FP which has flexible flanges FL and isconstituted by connecting the flange portions. Specifically, the slit ornotch according to the present invention exists not to allow to form aclosed plastic cylinder, thereby rendering itself entirely differentfrom that of the Japanese Patent Application Laid-Open No. 503672/1998in terms of its function and structure.

[0069] The slider to be used in the present invention is preferably aknocked-down slider. There is usable as a knocked-down slider, theslider as illustrated on FIG. 10 and FIG. 11 as disclosed by the presentinventor in Japanese Patent Application Laid-Open No. 130594/2001. Suchslider is fabricated by attaching the slider to a zipper in a state thata plate portion C-1 equipped with an inside guide S-1 is open andsubsequently closing the plate portion C-1.

[0070] There is disclosed as a knocked-down slider in U.S. Pat. No.5,070,583, a slider in which a constituent member for a slider outsideguide is enabled to open and close through a flexural axis parallel to aplane containing a bag body. However it is difficult from the aspect ofconstruction to apply such a slider to the zipper according to thepresent invention which requires stable attachment of the connectiongroove and opening plate. Accordingly, the slider to be used in order tocarry out the present invention is preferably slider which is disclosedin the Japanese Patent Application Laid-Open No. 130594/2001 (Heisei 13)and which is assembled by closing the guide constituent member through aflexural axis perpendicular to a plane containing a bag body asillustrated on FIG. 10 and FIG. 11.

[0071] In the case of carrying out the present invention by the use ofthe hermetically sealing zipper (FIG. 14 through FIG. 17) in which theengaging portion of the zipper in an engaged state is bonded with easilypeelable plastic layers, said zipper being described in the aforesaidJapanese Patent Application No. 345057/2000 relating to the proposal ofthe present inventor, at the time of assembling the slider by closingthe plate portion C-1 of the slider in the aforesaid Japanese PatentApplication Laid-Open No. 130594/2001, the slider needs to be assembledin a state that the zipper is kept engaged at the closing end positionthereof. In carrying out the present invention, when the insidedimension of the flange L2 between the hermetically sealing zipper andthe second zipper is set constant, the depth L4 of the connecting grooveS4 being larger enables the width of the opening plate S1 to be smaller,and conversely the depth L4 being smaller obliges the width S1 to belarger.

[0072] In order to miniaturize the slider, the width L5 of the openingplate S1 needs to be minimized and thus, the depth L4 of the connectinggroove S4 is preferably as close as possible to (L2 plus L3). Themaximum depth of the connecting groove S4 is the sum of (L2 plus L3) andthe thickness of the opening plate S1, but depth of the connectinggroove S4 is usually smaller than the maximum depth thereof. On theother hand, the length of the rib L2 in contact with the opening plateS1 is preferably in the range of 60 to 150% of the width of the zipperL1. The length of the rib L2, when being larger than the range, leads toan unreasonably large slider, whereas the length, when being smallerthan the range, brings about difficulty in closing the plate C-1 asexplained on FIG. 11, thereby making it impossible to steadily assemblethe hermetically sealing zipper while maintaining the engaged statethereof.

COMPARATIVE EXAMPLE 1

[0073] A measurement was made of opening strength (unit in KgF/5 cm) ofeach of 20 sheets taken out of 100 sheets lot of bag bodies eachequipped with a hermetically sealing zipper which was made of linear lowdensity polyethylene (L-LDPE), which had a length of 200 mm and whichwas fitted with a slider, and a width L1 of 3.5 mm, a flange insidedimension L2 of 1.5 mm and a rib thickness of 0.8 mm, each in FIG. 7-2.As a result, the average opening strength was 2.29 with a standarddeviation of 0.39. The bag bodies in the same lot as above in 20 sheetswere each equipped with the slider exemplified on FIG. 10 through FIG.13 and disclosed in Japanese Patent Application Laid-Open No.130594/2001, and were subjected to opening closing tests. As a result,all the bag bodies could be easily opened and closed.

COMPARATIVE EXAMPLE 2

[0074] A measurement was made of opening strength (unit in KgF/5 cm) ofeach of 20 sheets that were randomly taken out of 100 sheets lot of bagbodies each equipped with a hermetically sealing zipper which was madeof linear low density polyethylene (L-LDPE), which was fitted with aslider, an easily peelable layer in a thickness of 10 micron on thesurface of a continuous tightening wall, which was bonded through thecontinuous tightening rib and the easily peelable layer, and which haddimensions same as in Comparative Example 1. As a result, the averageopening strength was 3.90 with a standard deviation of 0.44. The bagbodies in the same lot as above in 20 sheets were each equipped with theslider same as in Comparative Example 1, and were subjected to openingclosing tests. As a result, 6 sheets of the bag bodies could be opened,3 sheets thereof could not be opened, and 11 sheets thereof wereincompletely opened. The slider, even if being capable of easily openingand closing the zipper having a proper opening strength, is sometimesincapable of opening or closing the zipper having a strong openingstrength. Accordingly, it is judged that the aforesaid slider isunapplicable to a zipper having a strong opening strength.

EXAMPLE 1

[0075] A measurement was made of opening strength (unit in KgF/5 cm) ofeach of 20 sheets that were randomly taken out of 100 sheets lot of bagbodies each equipped with a hermetically sealing zipper which was madeof linear low density polyethylene (L-LDPE), which was fitted with aslider, an easily peelable layer in a thickness of 10 micron on thesurface of a continuous tightening wall, which was bonded through thecontinuous tightening rib and the easily peelable layer, and which had awidth L1 of 3.5 mm, a flange inside dimension L2 of 3.0 mm and a ribthickness of 0.8 mm, each in FIG. 7-2. As a result, the average openingstrength was 4.08 with a standard deviation of 0.47. The bag bodies inthe same lot as above in 20 sheets were each equipped with the sliderwhich had a cross sectional configuration as illustrated on FIG. 3, andwhich was fitted with an opening plate having a width L5 of 4 mm, acover having a width of 1 mm and a connecting groove having a depth L4of 2 mm, and were subjected to opening closing tests. As a result, allthe bag bodies could be easily opened and closed. Accordingly, it isjudged that the aforesaid slider is applicable to a zipper, even if ithas a strong opening strength.

INDUSTRIAL APPLICABILITY

[0076] According to the plastic zipper equipped with a slider and a bagbody fitted with the zipper, the slider is imparted with an extremelyhigh opening strength in spite of its being miniatured and thereby iscapable of easily open a zipper in which hooks themselves or opening endedges themselves are bonded with easily peelable plastic layers for thepurpose of preventing unjust unsealing and which has a strong openingstrength.

1. A hermetically sealing plastic zipper equipped with a slider wherebysaid zipper is opened and closed, comprising a pair of male hook andfemale hook formed on plastic films, wherein said zipper is equippedwith flanges on the opening portion sides for each of the male hook andfemale hook thereof, the respective ends of the flanges are connected, awedged opening plate is pressed into the inside of a closed plasticcylinder which is constituted of the flange portions connectedrespective ends thereof and extended to said zipper in an engaged stateso as to firstly open said zipper, and after the zipper is opened, thetop portion of the flanges in a connected state is disconnected.
 2. Thehermetically sealing plastic zipper equipped with a slider according toclaim 1, wherein at the point of time and position where the opening endof the slider reaches the closing end of said zipper by the slidingoperation of the slider, the closed plastic cylinder which isconstituted of the flange portions connected to said zipper in anengaged state is not allowed to be formed thereat, so that thehermetical sealability of the zipper is maintained.
 3. The hermeticallysealing plastic zipper equipped with a slider according to claim 2,wherein a slit is made at a portion of the flanges corresponding to theopening plate at the closing end position of said zipper so as not toallow the closed plastic cylinder to be formed.
 4. The hermeticallysealing plastic zipper equipped with a slider according to claim 1,wherein a second zipper or a rib is installed at the end portions ofeach of the flanges at the opening portion side of the male hook andfemale hook for said zipper in an engaged state in order to connect saidend portions.
 5. The hermetically sealing plastic zipper equipped with aslider according to claim 4, wherein connected state of the end portionsof each of the flanges at the opening portion side of the male hook andfemale hook for said zipper in an engaged state is maintained byinstalling a connecting groove parallel to said zipper above the openingplate for the slider, placing a second zipper or a rib in saidconnecting groove, and installing a cover on the opening portion of saidconnecting groove.
 6. The hermetically sealing plastic zipper equippedwith a slider according to claim 4, wherein at the point of time andposition where the opening end of the slider reaches the closing end ofsaid zipper by the sliding operation of the slider, the closed plasticcylinder which is constituted of the flange portions connected to saidzipper in an engaged state is not allowed to be formed thereat, so thatthe hermetical sealability of the zipper is maintained.
 7. Thehermetically sealing plastic zipper equipped with a slider according toclaim 6, wherein a portion of the second zipper or the rib correspondingto the opening plate is crushed to flatness or cut off at the closingend position of said zipper so as not to allow the closed plasticcylinder to be formed.
 8. A bag body fitted with the hermeticallysealing plastic zipper equipped with the slider as set forth in claim 1.